This thesis is to identify the way So-hak education was accomplished in Yi-dynasty. It was commenced from the doubt that So-hak education in that times was not so successful as most precedent studies on So-hak resumed. And the conclusions are as follows: Firstly, most of students did not study So-hak hard since it was main book in preparing civil examination. Secondly, So-hak education in Yi-dynasty made poor progress from the early times to the end of Yi-dynasty. Thirdly, the reason why So-hak education failed was that the rulers could not catch hold of the way of students\' thinking and acting. Fourthly, the researchers who are to apply the principle of So-hak to present education should consider the conditions of successful application. Lsatly, any administrators who wish to succeed in applying new educational policies should consider students\' concerns.